Use of the trait-based approach in ecological restoration studies: a global review

Key message It is important to increase studies on effect traits in monitoring restoration areas, as well as to encourage the use of PFT in the planning of restoration programs. Abstract The trait-based approach can be used as an important tool along the whole process of restoration, since plant functional traits (PFT) explain how species respond to environmental changes (response traits) and how they affect ecosystem functioning and species coexistence (effect traits). We performed a systematic review to investigate to what extent PFT have been assessed in ecological restoration initiatives worldwide. We found 341 articles, the majority of them published during the last decade. Studies measuring response traits were more frequent than those on effect traits. Experimental designs were as frequent as active and passive restoration actions and only 8 studies involved restoration planning, which may be related to our limited knowledge about species’ trait–function relationships. The response–effect framework was present in only 2.3% of the articles, which shows a knowledge gap on the applicability of the functional approach in restoration areas. Most studies were developed in temperate biomes and young restoration sites (< 5 years); thus, little is known about the intermediate- and long-term effects of plants in their environment in a restoration context. Leaf traits were the most accessed in all studies. The increasing use of PFT in ecological restoration can build the bridge between theoretical and applied science. The low number of papers using PFT in restoration planning might be an alert of encouragement for the strengthening communication between researchers and practitioners. Our results may help in understanding the present use of the trait-based approach on ecological restoration science and shed light on research gaps.